(moved this post from 'XAMPP for Windows' to 'XAMPP for Mac OS X', since I'm using Mac)

I have installed XAMPP 1.7.2a and am trying to use the class Normalizer. According to the manual, this class should be present in PHP 5.3.3, but I get an error message saying 'Class Normalizer not found'. Is there something I need to do in the php.ini or include in my script in order to use this functionality? Or isn't XAMPP 1.7.2a using PHP5.3.3? I'm having this problem also when running from commandline, where "php -verson" prints"PHP 5.3.3 (cli) (built: Aug 22 2010 19:41:55)Copyright (c) 1997-2010 The PHP GroupZend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies"

Any ideas what's wrong with my environment or where I can search for an answer? I've tried to search in this forum without any success.